Exhaust system



Dec. 18, 1956 E. N. MORSE ETAL 2,774,394

EXHAUST SYSTEM Filed Aug. 18, 1951 2 Sheets-Sheet 1 PINCH- OFF INVENTORSE LIHU N. MORSE LLQYD'E. SHAW ATTORNEY BYg y g Dec. 18, 1956 E. N. MORSEE-rAL EXHAUST SYSTEM 2 Sheets-Sheet 2 Filed Aug. 18, 1951 l 3/ :UBUEKFIG. 4

INVENTORS Elihu N. Morse y Lloyd E.'Show a). ATTORNEY United StatesPatent EXHAUST SYSTEM Elihu N. Morse, Swampscott, and Lloyd .E. Shaw,Newburyport, Mass, assignors to Columhia Broadcasting System, Inc,Salem, Mass, a corporation of New York Application August 13, 1951,Serial No. 242,547 10 Claims. er. 141-55 This invention relates ingeneral to exhaust systems and in particular to protective devices foruse in such systems.

In the manufacture of electronic tubes as well as in other arts, when itis desired to exhaust the air from a system, pumps of various types areemployed. Where the degree or" vacuum desired is not great, a straightmechanical system may be used. To achieve lower pressure a diffusionpump is often inserted between the mechanical pump and the system to beexhausted.

Where high speed rotary exhaust machines are used, it has been founddesirable to use an oil diffusion pump with each head or tube carryingelement of the machine. The degree of vacuum, and speed of pumping areenhanced by such an arrangement, but several problems are presented whensuch a system is used. One diificulty encountered is the fouling of thejets of the diffusion pump by particles of glass which often find theirway into the system. When breakage occurs, glass fragments are drawninto the pump and improper operation or failure of the pump may result.Even apart from breakage, it sometimes happens that tiny glass particlesare present in the tubes being evacuated. Although these particles maybe quite firmly lodged within the tubes, the pumping action is oftensufficient to draw them from the tubes into the pump with seriousresults obtaining.

An obvious device for preventing these particles from reaching the pumpis a trap of some type placed in the line between the tube and the pump.In the past, such traps usually took the form of a chamber having twolines connected thereto. The input line from the tube was placed belowthe level of the output line to the pump and the action of gravity wasrelied upon to prevent glass particles from entering the output line andreaching the pump. Such traps were fairly ettective to remove heavyparticles, but were quite inefficient in removing small, light particleswhich often were borne on the stream of gas being drawn through thechamber into the output line and thence to the pump. A furtherdisadvantage attendant upon the use of such traps was the diflicultyinvolved in dismantling them from the system to remove whatever largerparticles may have been deposited within them. i 7

Therefore, it is an object of the present invention to provide a trapfor an exhaust system which adequately protects the pump being used inthe system.

it is a further object of the present invention to provide tration ofthe tubulation.

a trap for an exhaust system which operates efi'iciently to remove solidparticles of extremely small size and weight.

A still further object of the present invention is to. provide a trapwhich may be easily dismantled from the system for cleaning purposeswhen necessary.

In general, the present invention consists in an exhaust system whichutilizes a plurality of difl usion pumps, each of which has asubstantially Y-shaped structure. This structure resembles the type ofcoupling which is known as a Y branch, the Y being inverted withthe-stem directed upwardlytoward the system being exhausted, the

F 2,774,394 C P ten .18, 1956 2 straight leg leading downwardly to theintake line of a pump and the other or branch leg of the Y leadingdownwardly toa particle trap at an angle to the stem. Within the sternof the Y atube is centrally supported in communication with the .systembeing exhausted. This tube is bent to extend into the branch leg of theY which contains the particle trap, wherein it is also centrallysupported. Adjacent to the junction of the stern and branch leg of theY, but within the branch leg, an upwardly facing aperture is formed inthe tube. .Gases being exhausted from the system pass through the tube,out the aperture and thence to the'pump. Particles present in the systemalso pass through the tube, but by reason of their greater mass continuepast the aperture and into a removable container within the trap. For abetter understanding of the invention, together with other and furtherobjects, features, and advantages, reference should be made to thefollowing description which is to be read in connection with theaccompanying drawings in which:

Fig. 1 is a perspective view of a portion of a rotary exhaust machine;

Fig. 2 is a schematic view of certain elements of the exhaust machine;and

Fig. 3 is a sectional view of the intake stack and trap of the diffusionpump.

Fig. 4 is a view, partially schematic, illustrating working elements ofan exhaust machine.

leferringto Fig. l of the drawing there is illustrated in part a rotaryexhaust machine. Such machines, as in the present case, usually includea fixed plate having a plurality oi axial openings symmetricallyarranged in a circle. A rotatable plate usually similar to the fixedplate is lapped thereto, and a film of oil between the two plates aidsin maintaining a vacuum-tight seal when the rotatable plate is movedrelative to the fixed plate. The usual method of operation is to havemechanical pumps connected to certain of the openings in the fixed plateand electronic tubes placed in heads which are connected to the openingsin the rotatable plate through diffusion pumps. As the rotatable plateis indexed to place the proper openings thereof in register with theopenings of the fixed plate being pumped, evacuation of the tubesresults.

Referring now to Figs. 2 and 4 of the drawing, there is shownschematically an electronic tube 1 carried in a head 19 on the rotarytable 18 of an exhaust machine. The head l includes a length of rubbertubing into which the tubulation of the electronic'tube may be insertedin vacuum tight relationship therewith. A pinch ofi member may then beused to compress a portion or the rubber tubing to form a-closure belowthe furthest point of pene- Connected to the rubber tubing beneath thepinch off member is a metallic tube 2 which is also maintained in vacuumtight relationship therewith. Metallic tube 2 passes into the intakestack of a diffusion pump 3 which may conveniently be suspendedfrom therotary table 1% as shown, thus permitting gases to pass from electronictube 1 into the intake stack when the pinch ofi member is not set tocompress the rubber tubing. The outlet line 4; from diffusion pump 3leads to rotary valve 5 which includes two plates having circularlyarranged axial openings and sealed together in the manner discussedhereinabove. For purposes of simand 4. With these openings in. register,gases from the diffusion pump 3 are drawn through rotary valve 5 thencethrough connecting line 11 to a mechanical pump 10.;

Referring now to Fig 3, there is shown in section a portion of ditfusionpump 3. Tube 2 is inserted in,the intake stack of the pump and a vacuumseal is provided and provides a solid vacuum tight closure.

, of gases therethrough. V

therebetween. The vacuumseal includes an externally threaded malemember'13 at the top of the intake stack, cap 14wbich has a centralopening which clears tube 2 and has internal threads meshing with thoseof member 13'. When'cap 14 is tightneddownon' member 13, it bears upon"a washer 15 which has a'circular groove formedin its lower surface. Thegroove is matched to the end of the intake stack, and contains arubbergasket '17] to maintaina vacuum tight seal between washer 15 and the topof, the intake stackof diifusion pump 3. Washer 15 isi welded to tube 2and thus a seal-is provided betweentube 2 and the intake stack, the onlyinlet thereto being by Way of tube2..

' At a point on the intake stack adjacent cap 14 there is shown anadditional member- :21 for trapping foreign matter coursing through tube2. Member 21 is disposed at an angle to the intake stack and tube 2 isbent to enter member 21 at a central location. member 21 is open, but avacuum seal and cap 22 similar in structure to that on the intake stackcloses off the .open end. The cap in this case, however, has no opening.rninates'in an open end spaced from the end of member 21. Adjacent theend of tube 2 is'a barrier formed of a washer 23 welded to tube 2; Acylindrical cou- Tube 2 -ter-' The end of V 1 tainer 24 having anopening formed atone end .and 7 being closed at the other'end slidablyfits within mem ber' 21.

23, but disposed at a'point within member 21 an aperture 26 is formed intube 2.. Thu's,.when diffusion pump 3 is drawing gas throughthe intakestack, foreign matter carried by the stream of gas from electronic tubeI mounted above the intake .stack passes through tube 2.

The opening in container 24 is of sufficient diameter to loosely fitover the end of tube 2 but not its position over the end of tube 2.Above barrier washer V 1 At aperture 26, gases are diverted fromtube2'and' into I member 21, thence to the lower area of diffusion pump.

3, Foreign matter, being ofrgreater massthan thatof the gas molecules,continues past aperture 26 and is col- V lectedin container 24. 7

Obviously, when it is desired to remove foreign matter which collects incontainer 24, removal of cap 22 is easily efrected permitting access'forremoval and cleaning of container 24.

Although the foregoing specification describes the invention as embodiedin an exhaust system for electronic tubes, such detailed limitation'ofthe concepts is only for purposes of illustration of one form theinvention may take. General application of the concepts to any a systemwhere it is desired to separate materials of different mass is believedto'be withinthe' scope of the invention, which should be limited only bythe following claims. 7 7

What is claimed is: 1. An exhaust system' comprising, a

necting said intake stack to said member, and a trap 7 member to beevacuated, a pump havinganintake stackyaftube con- 60,

connected to said intake stack, said tube penetrating said f trap andterminating in an open end therein, said tube; having a lateral apertureformedtherein preventingthe a passage of .solid material, but'permittingthe 'free flow :2. An exhaust system comprisinga imember to beevacuated, a pump havingan intake stack and a tube in a side thereofthrough which the gaseous portion of said contents is caused to flow,solid'portionsof said said second chamber, solid particles continuingthroug contents continuing along said given path of travel through saidtube; V a

3. An exhaust system comprising a member to be evacuated, a pump havingan intake stack, a hollow t rap having one/end thereof attached to aside of said intake stack and communicating therewith through anaperture formed in the side thereof, a tube connecting said intake stackto said member, said tube being bent at an angle, a first portion ofsaidtube passing through said intake stack and a second portion thereofentering saidtrap, said 'tube terminating in 'an'open end within saidtrap and having an aperture formed in a side thereof at 'a point removedfrom said terrninating open end but within'lsaid trap, and removablemeans for vacuum sealing the other end of said trap. e

'4. Apparatus for separating solid particles from a stream of gascomprising, a first chamber containing gas at a relatively high pressureand-solid particles mixed therewith, a second chamber containing gas ata relatively low pressure, and a tube for passing said stream of gasfrom said first chamber to said second chamber,

said tube having an aperture formed in a ,wall thereof and terminatingin an open end within said second cham-, ber, pressure within saidsecond chamber being lower adjacent said aperture than at said open end,said stream of gas in said tube passing. through said aperture andcommunication with said first chamber, and ,extending' we downwardlythrough said secondchamber, the otheropen end of said tube beingdisposedwithiusaid branch chamber, said tube having an upwardly facingaperture formed f in a wall thereof at-a point within saidbranchchamber.

adjacent said second chamber, whereby said stream'of gas Passingthroughsaid tube is diverted through said aperture into said second chamber,solid particles con:

tinuing through said other open end of said tube into said branchchamber. 1

6. Apparatus for separating solid particles from a' s'tream of gascomprising, a first chamber containing gas ata relatively high pressureand solid particles mixed therewith, a'second chamber disposed beneathsaidfirst chamber, a pump for maintaining said second chamber." at arelatively low pressure, a branch chamber having one .end connected tosaid second chamber and depending downwardly therefrom, an open-endedtube'having f 'oneend thereof incommunication with said first chamber"and, extending downwardly through said s'econd ch'amber' intosaidbranch chamber, saidtube having an upwardly facingaperture formed in awall thereof at a point within said branch chamber, adjacent, saidsecond chamber, ,a

container loosely fitte'd'over thev other end of said tube within saidbranch chamber, aremovable cap for-vacuum sealing the other end of,saidbranch chamber, said cap maintaining said container in positionoverrisaid'other end offsaidtube whereby said stream of gas passingthrough said tube is diverted through said aperture into saidtube intosaidcontainer. V V r r I 7. Apparatus for removing solid matter from theintake stack of a diffusion pump comprising, a tube vacuumsealed in saidintake stack' for permitting the entry of "gases thereto, 'a'trap havingone endthereof joined tofth'e tside of said intake stack'andcommunicating with the interior thereof by'means of an aperture formedin a wall thereof, the longitudinal axis be saidi'trap 'being at anangle to that of said' intake stackj saidtube being bentthrough'an'angle such thata portion thereof is coaxial with said trap,.a container loosely fitted within said trap e Ji and having an open endenclosing one end of said tube, and a removable cap for vacuum sealingthe other end of said trap and for retaining said container within saidtrap, said tube having an aperture formed in a wall thereof wherebygases passing through said tube reach said intake stack through saidaperture and solid foreign matter proceeds through said tube and intosaid container.

8. Apparatus for filtering solid matter from the intake stack of adiffusion pump comprising, a tube sealed in said intake stack forpermitting the entry of gases thereto, a trap having one end thereofjoined to the side of said intake stack and communicating with theinterior thereof by means of an aperture formed in a wall thereof, thelongitudinal axis of said trap being at a first angle to that of saidintake stack, such that said trap depends downwardly therefrom, saidtube being bent at a second angle equal to said first angle such that afirst portion of said tube is coaxial with said intake stack and asecond portion of said tube is coaxial with said trap, a barrier memberof diameter larger than that of said tube welded thereto at a pointwithin said trap, an upwardly facing aperture being formed in the wallof said tube above said barrier member but within said trap, a containerhaving an open end of diameter larger than that of said barrier memberloosely fitted within said trap with the open end thereof enclosing theopen end of said tube and abutting said barrier member, and a removablecap for vacuum sealing the other end of said trap and for retaining saidcontainer in position whereby gases passing through said tube arediverted through said aperture formed therein and foreign solid mattercontinues through said tube into said container.

9. An exhaust system comprising, a rotary exhaust machine including afirst rotatable plate having a plurality of axial openings formedtherein symmetrically disposed in a circle adjacent the peripherythereof, a second fixed plate disposed beneath said first plate andhaving a similar plurality of axial openings formed therein about andadjacent the periphery thereof, said openings in said first plate beingin register with those of said second plate, a plurality of diffusionpumps each having an intake stack and an outlet line, means forconnecting each of said outlet lines to one of said openings in saidfirst plate, a rotary table having a similar plurality of heads andadapted to rotate with said first plate, a similar plurality of tubeseach connecting one of said heads to one of said intake stacks and eachbeing bent at an angle to the longitudinal axes thereof at a pointremote from the point of entry, a downwardly depending trap memberhaving one end thereof connected to the side of said intake stackthrough an aperture formed therein, said tube entering said trap memberand terminating in an open end adjacent the other end of said trapmember, said tube having an upwardly facing aperture formed in a wallthereof at a point adjacent the bend in said tube between said apertureand said terminating open end, whereby gases issuing from said head aredrawn through said tube and out said aperture to the intake stack ofsaid diffusion pump, solid particles being carried through theterminating open end of said tube and deposited in said other end ofsaid trap member.

10. An exhaust system comprising, a rotary exhaust machine having arotary table having a plurality of spaced heads disposed about andadjacent the periphery thereof, a first rotatable plate having a similarplurality of symmetrically arrayed axial openings formed therein, asimilar plurality of diffusion pumps connected between said heads andsaid openings in said first plate, a second fixed plate disposed beneathsaid first plate in vacuum tight relationship therewith and having asimilar plurality of symmetrically arrayed axial openings formedtherein, said openings in said first plate being in register with thoseof said second plate, means for indexing said first plate relative tosaid second plate to bring consecutive ones of said openings in saidfirst plate into register with those of said second plate, saidplurality of diffusion pumps including intake stacks disposed beneathsaid rotary table, means for separately connecting each of said intakestacks to one of said spaced heads of said rotary table, saidlastmentioned means each including a tube communicating with one of saidplurality of openings in said second plate, each of said intake stackshaving an aperture formed in a side thereof, hollow open ended membersof cross-sectional dimensions substantially similar to those of saidintake stacks, one end of each of said hollow members being connected atan angle to each of said intake stacks and depending downwardlytherefrom, the open end of each of said hollow members and the apertureof each of said intake stacks forming a mutual opening therebetween,said tube being bent to enter said hollow member at a central point andto follow the longitudinal axis thereof, said tube terminating in anopen end adjacent the other end of said hollow member, a cap threadablyattached to said other end of said hollow member in vacuum-tightrelationship therewith, a barrier washer attached to said tube at apoint adjacent the termination thereof, said tube having an upwardlyfacing aperture formed in a wall thereof at a point above said barrierwasher but within said hollow member, whereby gases issuing from saidheads are pumped through said tube and out said aperture to the intakestack of said difiusion pump, particles of foreign matter being carriedthrough said tube and deposited in said hollow member adjacent said cap.

References Cited in the file of this patent UNITED STATES PATENTS430,444 Smith June 17, 1890 1,461,173 Bennett July 10, 1923 2,162,209Trutner June 13, 1939 2,254,905 Mullan Sept. 2, 1941 2,265,381 MolloyDec. 9, 1941 2,542,636 De Groat -a Feb. 20, 1951 2,565,298 De Groat Aug.21, 1951

